An automobile air conditioner is a device for adjusting temperature of the inner space of an automobile by forcibly circulating air staying in the inner space of the automobile through a duct and causing the air to be cooled by the evaporator installed in the duct and to be discharged into the internal space of the automobile.
The evaporator of the air conditioner remains cool due to latent heat absorbed by the refrigerant as the refrigerant is evaporated. In addition, when relatively warm air meets the evaporator, moisture in the air is condensed to water on the surface of the evaporator.
This mechanism may not cause a serious problem if the air conditioner is persistently operated. However, if operation of the air conditioner is stopped, circulation of air is stopped and condensed water remains on the surface of the evaporator. Thereby, various kinds of microbes and germs reproduce in the condensed water, causing bad smell.
The biggest problems in conditioning air using an air conditioner is that water remaining on the evaporator due to the temperature of the evaporator of the air conditioner lower than that of air causes reproduction of germs and mold around the evaporator and the reproduced germs and mold move around in the air in the indoor space as the evaporator forcibly circulating the air to increase the heat exchange efficiency. Germs and mold are direct harm to human bodies and the bad smell caused by reproduction of germs is very unpleasant.
For air conditioners for domestic use or use in a building, after air cooling through the refrigerant is stopped, air is forcibly circulated for a certain time in order to vaporize condensed water on the surface of the evaporator to prevent the aforementioned problems. On the other hand, in the case of automobile air-conditioners, once the automobile is thus switched off, such operation cannot be performed. As a result, condensed water remains on the evaporator for a long time, causing reproduction of germs and microbes.
To partially prevent this problem, drivers form a habit of stopping cooling the air around five minutes before stopping the engines and letting air flow after air cooling is stopped. However, it is difficult to correctly determine the time to stop the engine. In addition, humid air begins to make the driver unpleasant from the time five minutes before the driver gets off the automobile.
It is widely known that germs are the cause of bad smells. Conventionally, various technologies of sterilization through direct radiation of ultraviolet light onto the evaporator have been proposed to suppress reproduction of germs. Application of an ionizer or a photocatalytic filter has also been proposed.
However, since plates of the operator for heat exchange are arranged very close to each other, ultraviolet light cannot reach the air deep in the space between the plates. Accordingly, radiation of ultraviolet light alone is not sufficient to suppress reproduction of germs around the evaporator. As a result, germs reproducing on the evaporator produce bad smell as in the previous case, and thus radiation of ultraviolet light onto the evaporator cannot be a solution. Thereby, the emotional quality of the evaporator is lowered for users who are exposed to bad smell.
Korean Patent Application Publication No. 2015-25967 proposes a technology of utilization of photocatalytic reaction. In contrast with the disclosure of this document, the catalytic reaction occurs only on the surface of a photocatalytic material, and thus active radical cannot be separated from the photocatalytic material. Accordingly, photocatalytic reaction cannot directly destroy germs reproducing on the evaporator.
In addition, the sterilization or deodorization efficiency of the ionizer is lower than that of photocatalytic reaction. Further, as the ionizer is installed so as not to obstruct airflow, the efficiency of the ionizer is further lowered.